Electromagnetic energy-absorbing optical product and method for making

ABSTRACT

An electromagnetic energy-absorbing optical product useful as a composite for coloring an opaque article such as a paint composite or car wrap is disclosed. The electromagnetic energy-absorbing optical product includes a polymeric substrate and a composite coating with the composite coating including first and second layers each containing a binding group component which together form a complimentary binding group pair.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-In-Part of U.S. Non-Provisionalapplication Ser. No. 14/569,955, filed on Dec. 15, 2014, the entiredisclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention broadly relates to optical products for use inautomotive applications and methods for their manufacture. Moreparticularly, the present invention relates to an electromagneticenergy-absorbing window film or an electromagnetic energy-absorbingcomposite for coloring an opaque article by application thereto, forexample a car wrap, that includes a composite coating including a firstlayer that includes a polyionic binder and a second layer that includesan electromagnetic energy-absorbing insoluble particle, wherein saidfirst layer and second layer each include a binding group componentwhich together form a complimentary binding group pair.

BACKGROUND OF THE INVENTION

Color has typically been imparted to optical products such as automotiveand architectural window films by use of organic dyes. Moreparticularly, the current commercial practice for producing dyed filmfrom polyester involves swelling of the molecular structure of thesubstrate in baths of hot organic solvent such as ethylene glycol duringthe dyeing process, as swelled polyester (particularly PET) films arecapable of absorbing organic dyes. These films and their manufacturingprocess suffer many drawbacks. Firstly, the substrates require exposureto organic solvents and elevated temperatures, which present bothmechanical and chemical challenges such as environmental hazards andcosts associated with storing the raw solvents and disposing of theresulting waste. Further, swelled substrates require special handling toavoid downstream stretching thereby decreasing the production yield.Next, the polyester elevated process temperatures and residual solventsin the substrate film after drying constrain downstream use andprocessing of substrates which in turn limits the potential end-useapplications for such dyed films. On the process side, the existingmethodology uses large volume dye baths which makes rapid color changewithin commercial manufacturing difficult. Finally, only a limitednumber of organic dyes are soluble and stable in the hot solventswelling media and many of those are often subject to degradation byhigh energy radiation (sub 400 nm wavelength) to which the substrate issubjected when used in window film applications, thereby shortening theuseful lifetime of the product.

To address these drawbacks, some film manufacturers have transitioned tousing a pigmented layer on the surface of a base polymeric film fortinting a polymeric film. For example, U.S. Published Application number2005/0019550A1 describes color-stable, pigmented optical bodiescomprising a single or multiple layer core having at least one layer ofan oriented thermoplastic polymer material wherein the orientedthermoplastic polymer material has dispersed within it a particulatepigment. As noted in this published application, these products cansuffer a myriad of processing and performance drawbacks. For example,layers of this type are typically applied as thin films and can employ arelatively high pigment concentration to achieve a desired tint level,particularly in automotive window films with a relatively high desiredlevel of darkening such as those with an electromagnetic energytransmittance in the visible region (or T_(vis)) of less than 50%. Thesehigh pigment concentrations are difficult to uniformly disperse withinthe thin layer. More generally, pigmented layers can suffer from greaterhaze and reduced clarity even in applications (for example architecturalwindow films) with a relatively moderate, low and even minimal levels ofdesired darkening.

Color also has previously imparted to optical products such ascomposites for coloring opaque articles (such as automotive panels, forexample) by application thereto, as described in U.S. Pat. No.5,030,513. Such composites are sometimes referred to in the art as paintcomposites or when applied to cars or automotive panels, car wraps. Inorder to achieve desired color saturation, however, typical thickness ofthe color containing layer is reported to be from about 0.1 to 3 mils(approximately 2,500 nm to 76,000 nm) at pigment concentrations of up to80%. In addition to difficulty in achieving uniform dispersion asmentioned above, these generally thicker and high-solids pigmentedcoatings can suffer from surface uniformity problems known in art asorange peel or surface mottling. While surfactants, flow control agentsand other similar additives may be used to minimize these issues, theyare often unable to achieve the level of uniformity as required bymodern day optical products. Thick solvent-borne as well as water-bornecoatings also require significant amount of energy to be applied to thesubstrate in order to dry or cure, making them less attractive from theenvironmental point of view.

A continuing need therefore exists in the art for an optical productthat meets all the haze, clarity, surface uniformity, UV-stability andproduct longevity demands of current commercial window films as wellautomotive window and vehicle coloring and/or protection films, whilealso being capable of manufacture by an environmentally friendly,aqueous-based coloring process performed preferably at ambienttemperatures and pressures.

SUMMARY OF THE INVENTION

An electromagnetic energy-absorbing optical product that includes apolymeric substrate and a composite coating, the composite coatinghaving a first layer that includes a polyionic binder and a second layerthat includes an electromagnetic energy-absorbing insoluble particle,wherein each of the first layer and the second layer include a bindinggroup component which together form a complimentary binding group pair,wherein the optical product is a composite for coloring an opaquearticle by application thereto.

Further aspects of the invention are as disclosed and claimed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in further detail below and withreference to the accompanying drawings, wherein like reference numeralsthroughout the figures denote like elements and in wherein

FIG. 1 is a schematic cross-section of an embodiment of theelectromagnetic energy-absorbing optical product of the presentinvention;

FIG. 2 is a schematic cross-section of an embodiment of theelectromagnetic energy-absorbing optical product of the presentinvention that includes a plurality of composite coatings;

FIG. 3 is a graph depicting electromagnetic transmittance data generatedfrom analysis of the electromagnetic energy-absorbing optical productsproduced in Example 2;

FIG. 4 is a graph depicting electromagnetic absorption data generatedfrom analysis of the electromagnetic energy-absorbing optical productsproduced in Example 4;

FIG. 5 is a graph depicting electromagnetic absorption data generatedfrom analysis of the electromagnetic energy-absorbing optical productsproduced in Examples 4 and 5;

FIG. 6 is a graph depicting electromagnetic absorption data generatedfrom analysis of the electromagnetic energy-absorbing optical productsproduced in Examples 4 and 6;

FIG. 7 is a graph depicting electromagnetic absorption data generatedfrom analysis of the electromagnetic energy-absorbing optical productsproduced in Examples 4 and 7. and

FIG. 8 is a graph depicting electromagnetic absorption data generatedfrom analysis of electromagnetic energy-absorbing optical productsproduced in Examples 2, 4 and 8.

FIG. 9 is a graph depicting electromagnetic absorption data generatedfrom analysis of electromagnetic energy-absorbing optical productsproduced in Examples 9 and 10.

DETAILED DESCRIPTION

As shown in FIGS. 1 and 2, the present invention is generally directedto an electromagnetic energy-absorbing optical product 10 comprising apolymeric substrate 15 and a composite coating 20. The composite coatingincludes a first layer 25 and a second layer 30. Preferably first layer25 is immediately adjacent to said polymeric substrate 20 at its firstface 28 and second layer 30 is immediately adjacent to first layer 25 atits opposite face 32. This first layer 25 includes a polyionic binderwhile the second layer 30 includes an electromagnetic energy-absorbinginsoluble particle. Each layer 25 and 30 includes a binding groupcomponent with the binding group component of the first layer and thebinding group component of the second layer constituting a complimentarybinding group pair. As used herein, the phrase “complimentary bindinggroup pair” means that binding interactions, such as electrostaticbinding, hydrogen bonding, Van der Waals interactions, hydrophobicinteractions, and/or chemically induced covalent bonds are presentbetween the binding group component of the first layer and the bindinggroup component of the second layer of the composite coating. A “bindinggroup component” is a chemical functionality that, in concert with acomplimentary binding group component, establishes one or more of thebinding interactions described above. The components are complimentaryin the sense that binding interactions are created through theirrespective charges.

The first layer 25 of the composite coating includes a polyionic binder,which is defined as a macromolecule containing a plurality of eitherpositive or negative charged moieties along the polymer backbone.Polyionic binders with positive charges are known as polycationicbinders while those with negative charges are termed polyanionicbinders. Also, it will be understood by one of ordinary skill that somepolyionic binders can function as either a polycationic binder or apolyanionic binder depending on factors such as pH and are known asamphoteric. The charged moieties of the polyionic binder constitute the“binding group component” of the first layer.

Suitable polycationic binder examples include poly(allylaminehydrochloride), linear or branched poly(ethyleneimine),poly(diallyldimethylammonium chloride), macromolecules termedpolyquaterniums or polyquats and various copolymers thereof. Blends ofpolycationic binders are also contemplated by the present invention.Suitable polyanionic binder examples include carboxylic acid containingcompounds such as poly(acrylic acid) and poly(methacrylic acid), as wellas sulfonate containing compounds such as poly(styrene sulfonate) andvarious copolymers thereof. Blends of polyanionic binders are alsocontemplated by the present invention. Polyionic binders of bothpolycationic and polyanionic types are generally well known to those ofordinary skill in the art and are described for example in U.S.Published Patent Application number US20140079884 to Krogman et al.Examples of suitable polyanionic binders include polyacrylic acid (PAA),poly(styrene sulfonate) (PSS), poly(vinyl alcohol) or poly(vinylacetate)(PVA, PVAc), poly(vinyl sulfonic acid), carboxymethyl cellulose (CMC),polysilicic acid, poly(3,4-ethylenedioxythiophene) (PEDOT) andcombinations thereof with other polymers (e.g. PEDOT:PSS),polysaccharides and copolymers of the above mentioned. Other examples ofsuitable polyanionic binders include trimethoxysilane functionalized PAAor PAH or biological molecules such as DNA, RNA or proteins. Examples ofsuitable polycationic binders include poly(diallyldimethylammoniumchloride) (PDAC), Chitosan, poly(allyl amine hydrochloride) (PAH),polysaccharides, proteins, linear poly(ethyleneimine) (LPEI), branchedpoly(ethyleneimine) BPEI and copolymers of the above-mentioned, and thelike. Examples of polyionic binders that can function as eitherpolyanionic binders or polycationic binders include amphoteric polymerssuch as proteins and copolymers of the above mentioned polycationic andpolyanionic binders.

The concentration of the polyionic binder in the first layer may beselected based in part on the molecular weight of its charged repeatunit but will typically be between 0.1 mM-100 mM, more preferablybetween 0.5 mM and 50 mM and most preferably between 1 and 20 mM basedon the molecular weight of the charged repeat unit comprising the firstlayer. Preferably the polyionic binder is a polycationic binder and morepreferably the polycationic binder is polyallylamine hydrochloride. Mostpreferably the polyionic binder is soluble in water and the compositionused to form the first layer is an aqueous solution of polyionic binder.In an embodiment wherein the polyionic binder is a polycation and thefirst layer is formed from an aqueous solution, the pH of the aqueoussolution is selected so that from 5 to 95%, preferably 25 to 75% andmore preferably approximately half of the ionizable groups areprotonated. Other optional ingredients in the first layer includebiocides or shelf-life stabilizers.

The second layer 30 of the composite coating 20 includes anelectromagnetic energy-absorbing insoluble particle. The phrase“electromagnetic energy-absorbing” means that the particle ispurposefully selected as a component for the optical product for itspreferential absorption at particular spectral wavelength(s) orwavelength ranges(s). The term “insoluble” is meant to reflect the factthat the particle does not substantially dissolve in the compositionused to form the second layer 30 and exists as a particle in the opticalproduct structure. The electromagnetic energy-absorbing insolubleparticle is preferably a visible electromagnetic energy absorber, suchas a pigment; however, insoluble particles such as UV absorbers or IRabsorbers, or absorbers in various parts of the electromagnetic spectrumthat do not necessarily exhibit color are also within the scope of thepresent invention. The electromagnetic energy-absorbing particle ispreferably present in the second layer in an amount of from 30% to 60%by weight based on the total weight of the second layer. In order toachieve the desired final electromagnetic energy absorption level, thesecond layer should be formed from a composition that includes theinsoluble electromagnetic energy-absorbing particle in the amount of0.25 to 2 weight percent based on the total weight of the composition.

Pigments suitable for use as the electromagnetic energy-absorbinginsoluble particle in a preferred embodiment of the second layer arepreferably particulate pigments with an average particle diameter ofbetween 5 and 300 nanometers, more preferably between 10 and 50nanometers, often referred to in the art as nanoparticle pigments. Evenmore preferably, the surface of the pigment includes the binding groupcomponent of the second layer. Suitable pigments are availablecommercially as colloidally stable water dispersions from manufacturerssuch as Cabot, Clariant, DuPont, Dainippon and DeGussa. Particularlysuitable pigments include those available from Cabot Corporation underthe Cab-O-Jet® name, for example 250C (cyan), 265M (magenta), 270Y(yellow) or 352K (black). In order to be stable in water as a colloidaldispersion, the pigment particle surface is typically treated to impartionizable character thereto and thereby provide the pigment with thedesired binding group component on its surface. It will be understood byordinary skill that commercially available pigments are sold in variousforms such as suspensions, dispersions and the like, and care should betaken to evaluate the commercial form of the pigment and modify it as/ifnecessary to ensure its compatibility and performance with the opticalproduct components, particularly in the embodiment wherein the pigmentsurface also functions as the binding group component of the secondlayer.

Multiple pigments may be utilized in the second layer to achieve aspecific hue or shade or color in the final product; however, it willagain be understood by ordinary skill that, should multiple pigments beused, they should be carefully selected to ensure their compatibilityand performance both with each other and with the optical productcomponents. This is particularly relevant in the embodiment wherein thepigment surface also functions as the binding group component of thesecond layer, as for example particulate pigments can exhibit differentsurface charge densities due to different chemical modifications thatcan impact compatibility.

Preferably the second layer of the composite coating further includes ascreening agent. A “screening agent” is defined as an additive thatpromotes even and reproducible deposition of the second layer viaimproved dispersion of the electromagnetic energy-absorbing insolubleparticle within the second layer by increasing ionic strength andreducing interparticle electrostatic repulsion. Screening agents aregenerally well known to those of ordinary skill in the art and aredescribed for example in U.S. Published Patent Application numberUS20140079884 to Krogman et al. Examples of suitable screening agentsinclude any low molecular weight salts such as halide salts, sulfatesalts, nitrate salts, phosphate salts, fluorophosphate salts, and thelike. Examples of halide salts include chloride salts such as LiCl,NaCl, KCl, CaCl₂, MgCl₂, NH₄Cl and the like, bromide salts such as LiBr,NaBr, KBr, CaBr₂, MgBr₂, and the like, iodide salts such as LiI, NaI,KI, CaI₂, MgI₂, and the like, and fluoride salts such as, NaF, KF, andthe like. Examples of sulfate salts include Li₂SO₄, Na₂SO₄, K₂SO₄,(NH₄)₂SO₄, MgSO₄, CoSO₄, CuSO₄, ZnSO₄, SrSO₄, Al₂(SO₄)₃, and Fe₂(SO₄)₃.Organic salts such as (CH₃)₃CCl, (C₂H₅)₃CCl, and the like are alsosuitable screening agents. Sodium chloride is typically a preferredscreening agent based on ingredient cost. The presence and concentrationlevel of a screening agent may allow for higher loadings of theelectromagnetic energy-absorbing insoluble particle such as those thatmay be desired in optical products with a T_(vis) of no more than 50%and also may allow for customizable and carefully controllable loadingsof the electromagnetic energy-absorbing insoluble particle to achievecustomizable and carefully controllable optical product T_(vis) levels.

Suitable screening agent concentrations can vary with salt identity andare also described for example in U.S. Published Patent Applicationnumber US20140079884 to Krogman et al. In some embodiments, thescreening agent concentration can range between 1 mM and 1000 mM orbetween 10 mM and 100 mM or between 30 mM and 80 mM. In some embodimentsthe screening agent concentration is greater than 1 mM, 10 mM, 100 mM or500 mM.

The second layer of the composite coating may also contain otheringredients such as biocides or shelf-life stabilizers.

In some embodiments, the electromagnetic energy-absorbing opticalproduct of the present invention may include a plurality of compositecoatings. For example, as depicted in FIG. 2, the optical product 10includes first and second composite coatings 20 and 20′, each with afirst layer and second layer, i.e. first composite coating 20 includingfirst layer 25 and second layer 30 and second composite coating 20′including first layer 25′ and second layer 30′. This depiction is notintended to be limiting in any way on the possible number of compositecoatings and one or ordinary skill will appreciate that this depictionis simply exemplary and illustrative of an embodiment with multiple or aplurality of composite coatings. The examples below further illustrateembodiments with a plurality of composite coatings.

For embodiments with a plurality of composite coatings, it will beappreciated that the electromagnetic energy-absorbing insoluble particlefor the second layer in each composite coating may be independentlyselected and that the second layers will in combination provide anadditive effect on the electromagnetic energy-absorbing character andeffect of the electromagnetic energy-absorbing optical product. For theembodiment shown in FIG. 2, this means that the second layer 30 of thefirst composite coating 20 and the second layer 30′ of the secondcomposite coating 20′ in combination provide an additive effect on theelectromagnetic energy-absorbing character and effect of theelectromagnetic energy-absorbing optical product. This additive effectcan be customized and carefully controlled in part by the concentrationof the electromagnetic energy-absorbing particle in each second layer asdispersed through the presence of the screening agent. For example, inan embodiment wherein the electromagnetic energy-absorbing particle is apigment, the second layers will in combination provide an additiveeffect on the visually perceived color of said electromagneticenergy-absorbing optical film product. In this embodiment, the pigmentsfor each second layer may be of same or similar composition and/or colorsuch that the additive effect is to increase intensity or depth ordarkness of the visually perceived color of the optical product or,stated another way, to reduce electromagnetic transmittance in thevisible wavelength range (or T_(vis)). In another embodiment, carbonblack is used as the pigment for at least one second layer and pigmentssuch as those listed above are used as pigments for the other secondlayer(s) such that the additive effect is a visually perceived darkenedcolor, also reducing electromagnetic transmittance in the visiblewavelength range (or T_(vis)). As discussed above, the present inventionmay be useful in products wherein relatively high levels of darkeningare desired. Accordingly, in a particularly preferred embodiment, theoptical products of the present invention have a T_(vis) of no more than50%. In yet another embodiment, the pigments for each second layer maybe of complimentary composition and/or color such that the additiveeffect is a visually perceived color different from and formed by theircombination of the individual pigments, for example an additiveperceived “green” color achieved by utilizing a blue pigment for onesecond layer and a yellow pigment for another second layer.

The polymeric substrate 15 may in the broadest sense be any substrateknown in the art as useable as an optical product component. A suitablepolymeric substrate is typically a flexible polymeric film, moreparticularly a polyethylene terephthalate (PET) film of a thickness ofbetween 12μ and 375μ or a polyvinyl butyral (PVB) film, preferably of athickness of between 0.01 to 1 mm and more preferably a thickness of 15to 30 mils. As prior art optical products for window film applicationsand employing dyes exhibit a variety of drawbacks, the polymericsubstrate is most preferably an undyed transparent polyethyleneterephthalate film. The polymeric substrate may also be a flexiblepolyurethane or flexible poly(vinyl chloride) film or may be a flexiblemultilayer polymeric composite film such as a polyurethane-basedmultilayer composite film as described for example in U.S. Pat. No.8,765,263, the disclosure of which is incorporated herein by reference.

The polymeric substrate may further include additives known the art toimpart desirable characteristics. A particular example of such anadditive is an ultraviolet (UV) absorbing material such asbenzotriazoles, hydroxybenzophenones or triazines. A useful polymericsubstrate with a UV absorbing additive incorporated therein is describedin U.S. Pat. No. 6,221,112, originally assigned to a predecessorassignee of the present invention.

In one embodiment wherein the polymeric substrate is a flexiblepolymeric film such as PET, the optical product may be a window film. Aswell known in the art, conventional window films are designed andmanufactured with levels of electromagnetic energy transmittance orreflectivity that are selected based on a variety of factors such as forexample product end use market application and the like. In oneembodiment, the optical product of the present invention has visiblelight transmittance or T_(vis) of no more than 50%, preferably no morethan 45% and more preferably no more than 40%. Such levels of visiblelight transmittance are often desired in window films with high levelsof darkening for certain automotive end use applications such assidelights. In another embodiment, the optical product of the presentinvention has visible light transmittance or T_(vis) of from 80 to 85%.Such levels of visible light transmittance are often desired in windowfilms with relatively moderate to low levels of darkening (typicallyalso with infrared absorption) for (to the extent permitted bygovernmental regulation) certain automotive end use applications such aswindscreens. In yet another embodiment, the optical product of thepresent invention has visible light transmittance or T_(vis) of no lessthan 85%, preferably no less than 88% and more preferably no less than90%. Such levels of visible light transmittance are often desired inwindow films with low to minimal levels of darkening for certainarchitectural end use applications.

The window films may optionally include layers or coatings known tothose of ordinary skill in the window film art. Coatings for example mayinclude protective hardcoats, scratch-resist or “SR” coats, adhesivelayers, protective release liners and the like. Layers may include forexample metallic layers applied by sputtering or other known techniques.Such layers or coatings may be components of the polymeric substrate.Further, the polymeric substrate may be a laminated or multilayerstructure.

In one embodiment, the optical product is an interlayer for laminatedglass. In this embodiment, the polymeric substrate is formed fromfilm-forming materials known in the art for this purpose, including forexample plasticized polyvinyl butyral (PVB), polyurethanes, polyvinylchloride, polyvinylacetal, polyethylene, ethyl vinyl acetates and thelike. A preferred film-forming material for the interlayer is aplasticized PVB such as that used in a commercially available fromEastman Chemical Company as SAFLEX® PVB interlayer. In this embodiment,the composite coating may be formed on at least one surface of thepolymeric substrate.

In an embodiment wherein the polymeric substrate is a flexible polymericfilm such as PET, the optical product may be a composite interlayer forlaminated glass including at least one safety film or interlayer. Thesafety film may be formed from film-forming materials known in the artfor this purpose, including for example plasticized polyvinyl butyral(PVB), polyurethanes, polyvinyl chloride, polyvinylacetal, polyethylene,ethyl vinyl acetates and the like. Preferred safety film is aplasticized PVB film or interlayer commercially available from EastmanChemical Company as SAFLEX® PVB interlayer. Preferably, the compositeinterlayer includes two safety films or one film layer and one coatinglayer, such as a PVB coating that encapsulate the polymeric substrate.Composite interlayers of this general type are known in the art and aredescribed for example in U.S. Pat. Nos. 4,973,511 and 5,091,258, thecontents of which are incorporated herein by reference.

In another embodiment, the optical product of the present invention is acomposite for coloring an opaque article by application thereto. Suchcomposites are known in the art and are sometimes referred to in the artas a colorant composite, paint composite or car wrap. More particularly,the article may be a vehicle selected from the group consisting of anautomobile, aircraft or boat; a vehicle panel or part such as a bumper,hood, fender or door; and a portion thereof. In this embodiment, thecomposite is applied to or adhered to the article using techniquesdescribed in the above-referenced '263 patent or in U.S. Pat. No.5,030,513, the disclosure of which is also incorporated herein byreference. One of ordinary skill will appreciate that the term“coloring” means for example imparting a color, multiple colors or anaesthetic color-based design or pattern to the opaque article.

In another aspect, the present invention is directed to a method forforming an electromagnetic energy-absorbing optical product. The methodof present invention includes (a) applying a first coating compositionto a polymeric substrate to form a first layer and (b) applying a secondcoating composition atop said first layer to form a second layer, saidfirst layer and said second layer together constituting a compositecoating. The first coating composition includes a polyionic binder andthe second coating composition includes at least one electromagneticenergy-absorbing insoluble particle and each of said first and secondcoating compositions include a binding group component which togetherform a complimentary binding group pair. The second coating compositionpreferably includes a screening agent as defined above.

In a preferred embodiment, at least one of the first and second coatingcompositions are an aqueous dispersion or solution and most preferablyboth of the first and second coating compositions are an aqueousdispersion or solution. In this embodiment, both applying steps (a) and(b) are performed at ambient temperature and pressure.

The optical products of the present invention are preferablymanufactured using known “layer-by-layer” (LbL) processes such asdescribed in Langmuir, 2007, 23, 3137-3141 or in U.S. Pat. Nos.8,234,998 and 8,689,726 and U.S. Published Application US 20140079884,co-invented by co-inventor Krogman of the present application, thedisclosures of which are incorporated herein by reference.

The following examples, while provided to illustrate with specificityand detail the many aspects and advantages of the present invention, arenot be interpreted as in any way limiting its scope. Variations,modifications and adaptations which do depart of the spirit of thepresent invention will be readily appreciated by one of ordinary skillin the art.

Example 1

To produce a coating composition suitable for forming the second layerof the composite coating of the present invention, 66.67 g of Cab-O-Jet352K, a dispersion of electromagnetic energy-absorbing insolubleparticle, a colloidally stable carbon black pigment commerciallyavailable from Cabot Corp., was diluted in deionized water to 1 wt %carbon black. As the surface of the carbon black particles arechemically functionalized with carboxylate groups by the manufacturer(thereby providing the binding group component), the pH of the solutionis adjusted to 9 with sodium hydroxide to ensure the carboxylate groupsare fully deprotonated. 2.92 g of sodium chloride are then added to thesolution (50 mM) to screen the electrostatic repulsion of the particlesin suspension and prepare them for deposition, where 50 mMNaCl has beendetermined to electrostatically screen the surface charge of the carbonblack particles without causing them to aggregate and precipitate fromsolution.

Example 2

To form the optical product of the present invention, a sheet ofpolyethylene terephthalate (PET) film (as substrate) with a thickness of75 microns was pretreated as known in the art by passing through aconventional corona treatment. A first layer was then formed on the PETsheet by spray coating, at ambient pressure and temperature, a firstcoating composition of 20 mM solution, based on the molecular weight ofthe charged repeat unit, of polyallylamine hydrochloride with anadjusted pH of 10. Excess non-absorbed material was rinsed away with adeionized water spray. The composition prepared in Example 1 above foruse in forming the second layer was then sprayed onto the surface of thefirst layer with excess material again rinsed away in a similar fashionwith the first layer and electromagnetic energy-absorbingparticle-containing second layer constituting the composite colorcoating of the present invention. Additional composite coatings wereapplied to the existing substrate using the same procedure with thevisible electromagnetic transmittance (T_(vis)) of the electromagneticenergy-absorbing optical product measured using a BYK HazeGard Pro afterapplication of 2, 4, 6, 8, 10 and 15 composite color coatings. Theresults of the T_(vis) measurements are graphically depicted in FIG. 3.

Example 3

To produce compositions suitable for forming the second layer of thecomposite coatings of the present invention, 100 g samples of adispersion of colloidally stable color pigment, for example CabotCab-O-Jet 250C cyan, 265M magenta, or 270Y yellow, were each diluted indeionized water to 1 wt % pigment to form five separate coatingcompositions. As the surface of the pigment particles are chemicallyfunctionalized with sulfonate groups by the manufacturer (therebyproviding the binding group component), the pH of the solution isadjusted to 9 with sodium hydroxide to ensure the carboxylate groups arefully deprotonated. 2.92 g of sodium chloride are then added to thesolution (50 mM) to screen the electrostatic repulsion of the particlesin suspension and prepare them for deposition, where 50 mM NaCl has beendetermined to electrostatically screen the surface charge of the carbonblack particles without causing them to aggregate and precipitate fromsolution.

Example 4

To form electromagnetic energy-absorbing optical products of the presentinvention, three sheets of polyethylene terephthalate (PET) film (assubstrate) with a thickness of 75 microns were pretreated as known inthe art by passing them through a conventional corona treatment. A firstlayer was then formed on each PET sheet by spray coating a 20 mMsolution, based on the molecular weight of the charged repeat unit, ofpolyallylamine hydrochloride with an adjusted solution pH of 10. Excessfirst layer material was rinsed away with a deionized water spray. Thecoating compositions prepared in Example 3 above were then each sprayedonto the surface of a separate coated sheet with excess material againrinsed away in a similar fashion. The first layer and the second layertogether constitute the composite coating of the present invention. Inthis example, three separate electromagnetic energy-absorbing opticalproduct samples, each using one of the coating compositions created inExample 3, were created by repeating the above deposition process foreach substrate 5 times, thereby depositing 5 composite coatings on eachsubstrate. The electromagnetic absorbance for each sample at variouswavelengths was then measured using a UV/vis spectrometer and is plottedagainst those wavelengths graphically in FIG. 4.

Example 5

To demonstrate the use of multiple electromagnetic energy-absorbinginsoluble particles in a single second coating composition andaccordingly a second layer, a green second coating composition wasproduced by forming a 50/50 mixture of the cyan- and yellow-pigmentcompositions prepared in Example 3. The procedure of Example 2 was thenutilized to form an electromagnetic energy-absorbing optical productwith the first layer of Example 2 and a second layer formed from thegreen composition described above. The deposition process was repeatedfor the substrate 5 times, thereby depositing 5 composite coatings onthe substrate. The electromagnetic absorbance at various wavelengths forthe sample was then measured using a UV-vis spectrometer and is plottedgraphically against those wavelengths along with the plots for theExample 4 samples with cyan and yellow pigment in FIG. 5.

Example 6

To demonstrate the use of multiple electromagnetic energy-absorbinginsoluble particles in a single second coating composition andaccordingly a second layer, a blue composition was produced by forming a50/50 mixture of the cyan- and magenta-compositions prepared in Example3. The procedure of Example 2 was then utilized to form anelectromagnetic energy-absorbing optical product with the first layer ofExample 2 and a second layer formed from the blue second coatingcomposition described above. The deposition process was repeated for thesubstrate 5 times, thereby depositing 5 composite coatings on thesubstrate. The electromagnetic absorbance at various wavelengths for thesample was then measured using a UV-vis spectrometer and is plottedgraphically along with the plots for the Example 4 samples with cyan andmagenta pigments in FIG. 6.

Example 7

To further demonstrate the use of multiple electromagneticenergy-absorbing insoluble particles in a single second coatingcomposition and accordingly a second layer, a red composition wasproduced by forming a 50/50 mixture of the yellow andmagenta-compositions prepared in Example 3. The procedure of Example 2was then utilized to form a colored optical product with the first layerof Example 2 and a second layer formed from the red compositiondescribed above. The deposition process was repeated for the substrate 5times, thereby depositing 5 composite colorant coatings on thesubstrate. The electromagnetic absorbance for the sample at variouswavelengths was then measured using UV/vis spectrometer and is plottedagainst those wavelengths along with the plots for the Example 4 sampleswith magenta and yellow pigments in FIG. 7.

Example 8

A film of reduced visible transmission and tunable color can be createdby depositing the desired number of composite coatings with carbon blackas the absorbing insoluble particle (Example 2) followed by the desirednumber of composite coatings with cyan, magenta and yellow pigments or acombination thereof (Examples 4-7). Here the deposition process wasrepeated for the substrate 5 times where the second layer containscarbon black followed by 5 times where the second layer contains cyanpigment, thereby depositing a total of 10 composite coatings on thesubstrate. The electromagnetic absorbance for the sample at variouswavelengths was then measured using UV/vis spectrometer and is plottedagainst those wavelengths along with the plots for a blackpigment-containing sample with five composite coatings generated in themanner of Example 2 and a cyan pigment-containing sample with fivecomposite coatings generated in the manner of Example 4 in FIG. 8.

Example 9

To form an electromagnetic energy-absorbing optical product of thepresent invention wherein the electromagnetic energy-absorbing opticalproduct is a composite for coloring an opaque article, a sheet ofthermoplastic polyurethane (TPU) film (as polymeric substrate) with athickness of 38 microns was pretreated as known in the art by passingthrough a conventional corona treatment. A first layer was then formedon the TPU sheet by spray coating, at ambient pressure and temperature,a first coating composition of 20 mM solution, based on the molecularweight of the charged repeat unit, of polyallylamine hydrochloride withan adjusted pH of 10. Excess non-absorbed material was rinsed away witha deionized water spray. The composition prepared in Example 1 above foruse in forming the second layer was then sprayed onto the surface of thefirst layer with excess material again rinsed away in a similar fashionwith the first layer and electromagnetic energy-absorbingparticle-containing second layer constituting the composite colorcoating of the present invention. 24 additional composite coatings withthe same first and second layers were applied to the existing substrateusing the same procedure. A polymeric top coat and a mounting adhesivewere then applied and the electromagnetic energy-absorbing opticalproduct was mounted on a metal panel for visible electromagneticreflectance (R_(vis)) measurement using a HunterLab® Prospectrophotometer. The results of the R_(vis) measurements for theelectromagnetic energy-absorbing optical product are graphicallydepicted in FIG. 9.

Example 10

The procedure of Example 9 was used to form an electromagneticenergy-absorbing optical product, in the form of a composite forcoloring an opaque article, using a pigment dispersion similar to thatdescribed in Example 3. More specifically, a composite for coloring anopaque article with a red color was created using a first coatingcomposition of 20 mM solution, based on the molecular weight of thecharged repeat unit, of polyallylamine hydrochloride with an adjusted pHof 10 to the first coating layer and Cabot Cab-O-Jet 1025R red pigmentfor use in forming the second coating composition for the second layer.Each layer was sprayed, and excess material rinsed away, in the mannerdescribed in Example 9. The polymeric substrate to which the compositecoating was applied was a sheet of thermoplastic polyurethane (TPU) filmwith a thickness of 38 microns which had been pretreated as known in theart by passing through a conventional corona treatment. 24 additionalcomposite coatings were applied with the same first and second layersusing the same procedure. A polymeric top coat and a mounting adhesivewere then applied and the electromagnetic energy-absorbing opticalproduct was mounted on a metal panel for visible electromagneticreflectance (R_(vis)) measurement using a HunterLab® Prospectrophotometer. The results of the R_(vis) measurements for theelectromagnetic energy-absorbing optical product are graphicallydepicted in FIG. 9.

Example 11

To form an optical product of the present invention wherein the opticalproduct is an interlayer for laminated glass, a plasticized PVB sheetcommercially available from Eastman Chemical Company as Saflex® SG 40was selected as the polymeric substrate. A first layer was then formedon the PVB sheet by spray coating, at ambient pressure and temperature,a first coating composition of 20 mM solution, based on the molecularweight of the charged repeat unit, of polyallylamine hydrochloride withan adjusted pH of 10. Excess non-absorbed material was rinsed away witha deionized water spray. The composition prepared in Example 1 above foruse in forming the second layer was then sprayed onto the surface of thefirst layer with excess material again rinsed away in a similar fashionwith the first layer and electromagnetic energy-absorbingparticle-containing second layer constituting the composite colorcoating of the present invention. 24 additional composite coatings withthe same first and second layers were applied to the existing substrateusing the same procedure. Utility of the resulting electromagneticenergy-absorbing optical product as an interlayer for laminated glasswas then demonstrated by forming using conventional and well-known glasslaminating methods and equipment a laminated glass product of two sheetsof ⅛-inch-thick glass with the electromagnetic energy-absorbing opticalproduct there-between. The laminated glass product was visuallyinspected to confirm coating integrity and laminate quality, includingthe absence of interlayer flow.

A person skilled in the art will recognize that the measurementsdescribed herein are measurements based on publicly available standardsand guidelines that can be obtained by a variety of different specifictest methods. The test methods described represents only one availablemethod to obtain each of the required measurements.

The foregoing description of various embodiments of the invention hasbeen presented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the preciseembodiments disclosed. Numerous modifications or variations are possiblein electromagnetic energy of the above teachings. The embodimentsdiscussed were chosen and described to provide the best illustration ofthe principles of the invention and its practical application to therebyenable one of ordinary skill in the art to utilize the invention invarious embodiments and with various modifications as are suited to theparticular use contemplated. All such modifications and variations arewithin the scope of the invention as determined by the appended claimswhen interpreted in accordance with the breadth to which they arefairly, legally, and equitably entitled.

That which is claimed is:
 1. An electromagnetic energy-absorbing opticalproduct comprising: a) a polymeric substrate and b) a composite coating,said composite coating comprising a first layer comprising a polyionicbinder and a second layer comprising an electromagnetic energy-absorbinginsoluble particle, wherein each of said first layer and said secondlayer include a binding group component which together form acomplimentary binding group pair; wherein said optical product is acomposite for coloring an opaque article by application thereto.
 2. Theoptical product of claim 1 wherein said composite coating has a totalthickness of 5 nm to 300 nm.
 3. The optical product of claim 1 whereinsaid first layer is immediately adjacent to said polymeric substrate atits first face and said second layer is immediately adjacent to saidfirst layer at its opposite face.
 4. The optical product of claim 1wherein said electromagnetic energy-absorbing particle includes aparticulate pigment, the surface of which includes said binding groupcomponent of said second layer.
 5. The optical product of claim 1further comprising a second composite coating, said second compositecoating comprises a first layer comprising a polyionic binder and asecond layer comprising an electromagnetic energy-absorbing particle,wherein said first layer of said second composite coating and saidsecond layer of said second composite coating, comprise a complimentarybinding group pair.
 6. The optical product of claim 1 wherein saidsecond layer of said first composite coating and said second layer ofsaid second composite coating in combination provide an additive effecton the electromagnetic energy-absorbing character and effect of theelectromagnetic energy-absorbing optical product.
 7. The optical productof claim 1 wherein said opaque article is selected from the groupconsisting of a vehicle; a vehicle panel, a vehicle part and a portionthereof.
 8. The optical product of claim 1 wherein said vehicle is anautomobile, aircraft or boat.
 9. The optical product of claim 7 whereinsaid electromagnetic energy-absorbing particle of said second layer ofsaid first composite coating and wherein said electromagneticenergy-absorbing particle of said second layer of said second compositecoating each comprise a pigment.
 10. The optical product of claim 1wherein said electromagnetic energy-absorbing particle of said secondlayer of said first composite coating and said electromagneticenergy-absorbing particle of said second layer of said second compositecoating provide an additive effect on the visually perceived color ofsaid optical product.
 11. The optical product of claim 1 wherein atleast one of said first layer and said second layer of said compositecoating is formed from an aqueous solution.
 12. A electromagneticenergy-absorbing optical product comprising: a) a polymeric substrateselected from the group consisting of a polyvinyl butyral film, aflexible polyurethane film, a flexible poly(vinyl chloride) film and aflexible multilayer polymeric composite film; b) a composite coating,said composite coating comprising a first layer comprising a polyionicbinder and a second layer comprising a electromagnetic energy-absorbinginsoluble particle, wherein each of said first layer and said secondlayer include a binding group component which together form acomplimentary binding group pair.
 13. The optical product of claim 12wherein said optical product has a Tvis of no more than 50%.
 14. Theoptical product of claim 12 wherein said optical product has a Tvis ofno less than 80%.
 15. The optical product of claim 14 wherein saidpolymeric substrate is a flexible multilayer polymeric composite film.16. The optical product of claim 14 wherein said flexible multilayerpolymeric composite film is a polyurethane-based flexible multilayercomposite film.
 17. The optical product of claim 14 wherein saidpolymeric substrate is a polyvinyl butyral film.
 18. The optical productof claim 14 wherein said optical product is a composite for coloring anopaque article by application thereto.